ASTRONOMY PICTURE OF THE DAY August 1, 2026 at 05:00PM What's happening to this cloud? Ice crystals in a distant cirrus cloud are acting like little floating prisms. Known informally as a fire rainbow for its flame-like appearance, a circumhorizon arc appears parallel to the horizon. For a circumhorizontal arc to be visible, the Sun must be at least 58 degrees high in a sky where cirrus clouds present below -- in this case cirrus fibratus. The numerous, flat, hexagonal ice-crystals that compose the cirrus cloud must be aligned horizontally to properly refract sunlight in a collectively similar manner. Therefore, circumhorizontalarcs are somewhat unusual to see. The featured fire rainbow was photographed in 2021 near North Fork Mountain in West Virginia, USA. Image: https://ift.tt/maIPnih via NASA https://ift.tt/5r1atfc APOD --> https://ift.tt/VJ8QchF
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